The bioavailability of lead and cadmium from municipal solid waste incinerator flyash

Particulate ashes entrained in the gas stream of municipal solid waste incinerators exhibit high concentrations of heavy metals on the surface and within the matrix. A finite quantity of this flyash is emitted into the atmosphere through fugitive dust and stack emissions. Inhalation or ingestion could result in metal poisoning depending upon the bioavailability of the metals from the ash.; The bioavailability of lead and cadmium from MSW incinerator flyash was examined in laboratory rats to supply accurate toxicological information. Gavage and intratracheal instillation were techniques employed to examine the ingestion and inhalation routes of exposure.; Samples of ash were obtained from two incinerators to compare relative toxicity based upon differing plant configuration. Samples were fractionated into three particle size ranges for experimentation. Laboratory batch and packed column extractions with physiologically applicable flow rates and pHs were carried out to provide potential explanations for mechanisms of in-vivo absorption of lead and cadmium.; Levels of lead detected twenty-four hours after G.I. tract instillation of flyash were found to plateau rapidly in the blood. Response curves for levels of lead in kidneys were found to be dose dependent, with less than 1.0% of total lead in the ash available for absorption. Cadmium was not detected in any organs after dosing through the G.I. tract.; Intratracheal instillation of flyash resulted in at least an order of magnitude greater absorption of lead into the kidney after twenty-four hours as compared to G.I. tract absorption. Concentrations of lead in the blood and liver were found to be variable.; Lung retention of metal twenty-four hours after intratracheal instillation was found to be dependent upon particle size and total amount of metal. Cadmium was found to be retained in the lung but was not detected in any other organs.